There are two wrestling events at the Olympics; Greco-Roman and freestyle.

In Greco-Roman wrestling competitors use only their arms and upper bodies to attack their opponent.

Holding an opponent below the waist is forbidden, as is using legs actively in any hold, and a wrestler must fall to the mat with his opponent if he has forced him down.

Freestyle wrestlers are allowed to use their legs and holds are largely unlimited so long as they are not deemed dangerous, which means they are not allowed to lock their feet around the head, neck or body of their rivals.

As a result Greco-Roman is the slower discipline, although both forms subscribe to the same basic format.

In Athens, where women will compete for the first time, each weight category will consist of up to 20 wrestlers, randomly divided into pools.

Wrestlers will fight each other within their pool, with the winners of the two four-man pools qualifying for the semi-finals.

WEIGHT CATEGORIES

Men's Greco-Roman55kg; 60kg; 66kg; 74kg; 84kg; 96kg; 120kg

Men's freestyle55kg; 60kg; 66kg; 74kg; 84kg; 96kg; 120kg

Women's freestyle48kg; 55kg; 63kg; 72kg

The winners of the three-man pools progress to a knockout with the two winners moving on to the last four.

From the semi-final, the competition is a straight knockout, with the winners progressing to the final and the losers competing for the bronze.

A bout is fought within an eight-metre yellow wrestling area, which is bordered by a red passivity zone on a 12m by 12m mat.

The action lasts for two three-minute rounds, which are separated by a 30-second break and there is no difference in the manner in which the two are judged and scored.

An athlete's aim in each is to prove their control of the bout by pinning an opponent's shoulders to the mat, a move known as a fall which automatically ends a match.

A victory can also be gained by winning 10 points in a bout, known as technical superiority, or by finishing the bout with more points.

A wrestler must have scored at least three technical points to win.

If that has not been achieved, or the points score is tied, then the bout continues until the next person scores a point to win. If no point is scored in three minutes, the judges decide on the winner.

Wrestlers have to enter into the spirit of the game and can be found guilty of passivity if they fail to initiate effective holds, obstruct or prevent their opponent from wrestling.

If the referee decrees a case of passivity, an initial warning is given before points are awarded to the opponent.